1. Field of the Invention
The present invention relates to a battery compartment for a condenser microphone effectively preventing noise generated by a high-frequency current propagating from a battery unit to an electric circuit.
2. Related Background Art
An end of a battery must be hooked with a fingernail to remove the battery from a battery compartment of a conventional device that includes, as a power source, a cylindrical dry-cell battery, such as a size AA battery, loaded in the battery compartment. The end of the battery, however, cannot be readily hooked with a fingernail for removal in the case where a spring terminal provided inside the battery compartment strongly holds the terminal of the battery or in the case where the space is narrow between the end of the battery and the internal wall of the battery compartment. To address the circumstances, a ribbon is provided inside a battery compartment to facilitate removal of the battery, as disclosed in Japanese Unexamined patent application Publication No. 2004-039598.
Such a ribbon is used to facilitate removal of the battery in a condenser microphone that includes an internal battery as a power source or a power supply that includes a battery to supply external power to a microphone provided with no battery. In general, a condenser microphone is supplied with power from a phantom power supply apparatus if it is connected to the power supply apparatus, while being supplied with power from a battery loaded in a microphone main body or a power supply if it is not connected to a phantom power supply apparatus.
A typical power supply provided with a conventional battery compartment for a condenser microphone is illustrated in FIGS. 5 to 8C. The power supply 100 has an output terminal 101, an input terminal 102, and a battery compartment 103 loaded with a battery 107. The output terminal 101 is connected to an external phantom power supply apparatus through a microphone cable (not shown in the drawings) having a 3-pin microphone connector. The 3-pin input terminal 102 is connected to a condenser microphone main body (not shown in the drawing). The battery compartment 103 includes a lid 104, a battery space 105, and a ribbon 106. The ribbon 106 is composed of woven non-conductive fabric or a resin film. One end portion of the ribbon 106 is fixed to the internal wall of the battery space 105.
To load the battery 107, the ribbon 106 is placed along the internal wall of the battery space 105, as shown in FIG. 8A; the battery 107 is placed on the ribbon 106; and the lid 104 is closed. To remove the battery 107, the lid 104 is opened and the other end portion of the ribbon 106 is held and pulled up, as shown in FIGS. 8B and 8C. Thus, the battery 107 can easily be removed from a battery outlet, which is an open portion of the battery space 105.
Strong electromagnetic waves applied to a condenser microphone or a power supply connected thereto cause a high-frequency current to flow into the condenser microphone or the power supply. A semiconductor of an electric circuit inside the condenser microphone or the power supply detects the current, which generates noise. In a condenser microphone or a power supply that includes a battery in particular, a high-frequency current from a battery compartment propagates to an electronic circuit and generates noise. With recent spread of cellular phones, they are more frequently used proximate to condenser microphones or power supplies, thus causing the circumstance to be more significant.